The present invention is directed to a chamber door lock for a hydraulically operated roller lock system. Such a system is described for example in Environmental Tectonics Corporation data sheet 901D-686-3M titled "Roller Lock Door System". In such a system, the chamber door is mounted on a "C" frame journaled on a hinge pin which is vertically movable between up and down positions by a hydraulic cylinder. Each side of the door is provided with a column of spaced door block weldments. A column of spaced chamber block weldments is also mounted on each side of the chamber face, in juxtaposition with the door block weldments. The chamber block weldments are stationary. A locking bar is located on each side of the chamber face near the chamber block weldments. Each locking bar is vertically movable between up and down positions by means of a hydraulic cylinder. A column of spaced roller assemblies is coupled to each locking bar for vertical movement therewith. Each roller assembly includes an arm. The arm is pivotably mounted at one end on a chamber block weldment and supports a roller at its other end coupled to the locking bar.
To open the chamber face, the locking bars are raised by their hydraulic cylinders and then the door cylinder is actuated to lift the hinge pin and door to an uppermost position wherein the door block weldments clear the raised locking bar rollers. The chamber door is then swung on the hinge pin away from the chamber face. The door block weldments pass through the spaces between the chamber block weldments on each side of the chamber face. To seal the chamber, the door is swung on the hinge pin against the chamber face while the locking bars are raised. The door block weldments pass through the spaces between the chamber block weldments on each side of the chamber face. The door cylinder is then actuated to pull the hinge pin and door downwardly so that the door block weldments are aligned with and are behind the chamber block weldments. This prevents the door from being swung open and brings the door gasket in position along the periphery of the chamber face opening. To seal the chamber face, the locking bar cylinders are actuated to pull the locking bars downwardly thereby pivoting the roller assembly arms downwardly until the arms are below their horizontal or center positions. The rollers contact the door block weldments on both sides of the door and urge the door against the chamber face while compressing the door gasket.
When each locking bar reaches the lowermost position, it trips a limit switch thereby allowing the chamber to be pressurized via an operator control. The chamber pressure tends to urge the door away from the chamber face thereby urging the door block weldments against the rollers. The door block weldments assist in holding the locking bars in their lowermost positions because the force exerted on the rollers tends to keep the roller assembly arms below their center positions.
If the chamber door has not been lowered to its lowermost position when the locking bar cylinders are actuated, the rollers may override the door block weldments and lock up on the weldment bottom edges as the locking bars reach their lowermost positions. The roller arms are essentially locked below their center positions but the rollers are not correctly positioned relative to the door block weldments. When the chamber is pressurized, the chamber pressure tends to force the door outwardly whereby the door block weldments may ride over the rollers allowing the door to separate from the chamber.
Also, although the locking bars and chamber door may be brought to their lowermost positions, so that a proper seal is obtained at the chamber face before the chamber is pressurized, an operator may mistakenly attempt to raise the chamber door (by actuating the door cylinder) without first raising the locking bars. If the door is raised sufficiently, the door block weldments may clear the rollers whereby the chamber pressure can cause the door to separate from the chamber face.
The problems solved by the present invention are that of preventing the chamber from being pressurized unless the chamber door and locking bars are in their lowermost positions so that the chamber face is properly sealed, and that of preserving the seal by preventing the chamber door from being raised while the chamber is pressurized.